This is a prospective, randomized, double blind, controlled trial. Following detailed past medical history assessment, two days before the surgical procedure neurocognitive function tests, depression and anxiety tests were carried out to assess the participants. Neurocognitive and anxiety tests were repeated on the 6th day after surgical procedure. A battery of tests lasting approximately 40 minutes were administered by a trained neuropsychologist from the Clinical Hospital Center, Split in a standardized fashion, at the same time of the day (10:00 AM) and in the same room at the Cardiac surgery ward. The investigators used a validated battery of tests which enabled the assessment of psychomotor speed, visual-motor coordination, concentration, attention, short-term memory and aspects of executive functioning. The evaluation was based on the following tests: Mini Mental State Examination (MMSE), Wechsler Memory Scale (WMS I & II), Trail Making Test (TMT A & B), Symbol Digit Modalities Test (SDMT), Controlled Oral Word Association Test (COWAT) and PsychE computer test. All of the tests except TMT A & B have alternate forms. Croatian versions of Beck Depression Inventory-Second Edition (BDI II) and State-Trait Anxiety Inventory (STAI-M) were used for preoperative depression and trait and state anxiety assessment, respectively.